Signal transmission method of semiconductor integrated circuit for transmitting signal to a plurality of stacked semiconductor chips

ABSTRACT

A semiconductor integrated circuit includes a plurality of semiconductor chips stacked in a multi-layer structure; a correction circuit in each semiconductor chip configured to reflect a delay time corresponding to the position of the chip in the stack into an input signal to output to each semiconductor chip; and a plurality of through-chip vias formed vertically through each of the semiconductor chips and configured to transmit the input signal to the semiconductor chip.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.13/270,437 filed on Oct. 11, 2011, which claims priority of KoreanPatent Application No. 10-2011-0072456, filed on Jul. 21, 2011. Thedisclosure of each of the foregoing application is incorporated hereinby reference in its entirety.

BACKGROUND

1. Field

Exemplary embodiments of the present invention relate to semiconductordesign technology, and more particularly, to a semiconductor integratedcircuit having a multilayer structure and a signal transmission methodthereof.

2. Description of the Related Art

In general, packaging technology for semiconductor integrated circuitshas features for miniaturization and mounting reliability. A stackpackage may have the features of high performance and small circuitsize.

In the semiconductor industry, a “stack” means vertically stacking atleast two or more semiconductor chips or packages. When a stack packageis used in a semiconductor memory device, a memory capacity of thesemiconductor memory device may be two or more times larger than amemory capacity of a semiconductor memory device that does not implementa stack package. Furthermore, the stack package not only increases thememory capacity, but it also more efficiently uses the mounting area.Also, the stack package has higher packaging density.

The stack package may be fabricated by the following methods. First,individual semiconductor chips may be stacked, and then packaged.Second, packaged individual semiconductor chips may be stacked. Theindividual semiconductor chips of the stacked semiconductor package areelectrically coupled through metallic wires or by through silicon vias(TSVs). The stack package using TSVs has a structure where the physicaland electrical coupling between semiconductor chips are verticallyachieved by TSVs formed in the respective semiconductor chips. Forreference, various methods are used to form the TSVs such as a via firstprocess, a via last process, a via last from backside and so on.

FIGS. 1A to 1G illustrate a method for forming a TSV. In the followingdescriptions, a via middle process will be illustrated as an example.The via middle process forms a TSV in a state where a part of a circuitis formed in an active layer.

Referring to FIG. 1A, an active layer 104 and a transistor 106 areformed on a wafer substrate 102. Referring to FIG. 1B, the active layer104 and the wafer substrate 102 are etched to form a groove with adesignated depth, and the groove is filled with a conductive material,such as a metal (for example, copper), to provide the base of a TSV 108.

Referring to FIG. 1C, an interlayer dielectric layer 110 is formed onthe active layer 104, and metal lines 112 are formed in the interlayerdielectric layer 110. The metal lines 112 are electrically coupled tothe TSV 108 and the transistor 106. A TSV pad 114 is formed on the metalline above the TSV 108, and the TSV pad 114 will be used to electricallycouple the TSV 108.

Referring to FIG. 1D, when the TSV pad 114 is formed, a bump 116 isformed and electrically coupled to the TSV pad 114. The bump 116 is acomponent that electrically couples the TSV 108 to a TSV formed inanother semiconductor chip that is stacked. A carrier 118 issubsequently formed over the interlayer dielectric layer 110. Thecarrier 118 is a component that fixes a wafer during a wafer thinningprocess (shown in FIG. 1E), which is performed to expose one end of theTSV 108.

Referring to FIG. 1E, the wafer thinning process is performed to exposeone of the ends of the TSV 108. A bump 120 is formed at the exposed endof the TSV 108, which was exposed by the wafer thinning process. Then,referring to FIG. 1F, the carrier 118 is removed. Accordingly, asemiconductor chip 100A for stacking is fabricated, and the bumps 116and 120 are provided on the top and bottom of the semiconductor chip100A.

Referring to FIG. 1G, the semiconductor chips 100A and 100B are stackedand the electrically coupled to each other through the bumps that areconnected to the TSVs.

Hereafter, a signal transmission path through the plurality ofvertically stacked semiconductor chips (hereafter, referred to as“semiconductor integrated circuit”) will be described.

FIG. 2 is a side view of a semiconductor integrated circuit illustratinghow a signal applied to the semiconductor integrated circuit istransmitted to the respective semiconductor chips through TSVs. Therespective semiconductor chips and the TSVs in the semiconductorintegrated circuit of FIG. 2 may be illustrated similarly to FIGS. 1A to1G. For illustration purposes, however, they are conceptuallyillustrated.

Referring to FIG. 2, a signal SIG is buffered into an internal signalSIG1 through a buffer BUF provided in a first semiconductor chip CHIP1,and transmitted to a TSV TSV1 while applied to the first semiconductorchip CHIP1. Furthermore, a signal SIG2 transmitted from the TSV TSV1 istransmitted to a TSV TSV2 while applied to a second semiconductor chipCHIP2. Furthermore, a signal SIG3 transmitted from the TSV TSV2 istransmitted to a TSV TSV3 while applied to a third semiconductor chipCHIP3. Furthermore, a signal SIG4 transmitted from the TSV TSV3 isapplied to a fourth semiconductor chip CHIP4.

When the respective signals SIG, SIG1, SIG2, SIG3, and SIG4 aretransmitted, a delay time caused by the buffer BUF provided in the firstsemiconductor chip CHIP1 may be represented by ‘tDbuf’, and a delay timecaused by each of the TSVs TSV1, TSV2, and TSV3 may be represented by‘tDtsv’. Referring to FIG. 3, the signal SIG1 applied to the firstsemiconductor chip CHIP1 is delayed by ‘tDbuf’ from the signal SIG, thesignal SIG2 applied to the second semiconductor chip CHIP2 is delayed by‘tDbuf+tDtsv’ from the signal SIG, the signal SIG3 applied to the thirdsemiconductor chip CHIP3 is delayed by ‘tDbuf+(tDtsv*2)’ from the signalSIG, and the signal SIG4 applied to the fourth semiconductor chip CHIP4is delayed by ‘tDbuf+(tDtsv*3)’ from the signal SIG. In short, thesignals SIG1, SIG2, SIG3, and SIG4 are each increasingly delayeddepending on the number of TSVs that the signal is transmitted through.Because of the delays caused by the TSVs TSV1, TSV2, and TSV3, skews mayoccur.

The signal delay as a result of the TSVs TSV1, TSV2, and TSV3 is causedby a parasitic resistor and a parasitic capacitor (R*C) formed by theTSVs TSV1, TSV2, and TSV3 and the bumps of the TSVs. The skews caused bythe signal delay limits high-speed operation.

SUMMARY

An embodiment of the present invention is directed to a semiconductorintegrated circuit capable of minimizing skews occurring between aplurality of stacked semiconductor chips, and a signal transmissionmethod thereof.

In accordance with an embodiment of the present invention, asemiconductor integrated circuit includes: a plurality of semiconductorchips stacked in a multilayer structure; a correction circuit in eachsemiconductor chip configured to reflect a delay time corresponding tothe position of the chip in the stack into an input signal to output toeach semiconductor chip; and a plurality of through-chip vias formedvertically through each of the semiconductor chips and configured totransmit the input signal to the semiconductor chip.

In accordance with another embodiment of the present invention, asemiconductor integrated circuit includes: a plurality of secondsemiconductor chips sequentially stacked over a first semiconductor chipthe first semiconductor chip configured to transmit an external inputsignal to the second semiconductor chips; a correction circuit in thefirst semiconductor chip configured to reflect a delay timecorresponding to the position of the chip in the stack into the externalinput signal to output to the first semiconductor chip; a correctioncircuit in each of the second semiconductor chips configured to reflecta delay time corresponding to the position of the chip in the stack intoan input signal to output to the second semiconductor chips; and aplurality of first through-chip vias formed vertically through theplurality of second semiconductor chips, respectively, and configured totransmit the external input signal transmitted from the firstsemiconductor chip as the input signal to the second semiconductorchips, respectively.

In accordance with yet another embodiment of the present invention, asignal transmission method of a semiconductor integrated circuit, whichtransmits a signal applied from an external circuit to the plurality ofstacked semiconductor chips, includes: calculating delay times thatoccur between the plurality of stacked semiconductor chips during a testmode; and reflecting the delay times into signals transmitted to therespective semiconductor chips and outputting the signals into therespective semiconductor chips, during a normal mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1G illustrate a method for forming a TSV.

FIG. 2 is a configuration diagram of a conventional semiconductorintegrated circuit illustrating a signal transmission method of theconventional semiconductor integrated circuit.

FIG. 3 is a timing diagram illustrating the signal transmission methodof the semiconductor integrated circuit of FIG. 2.

FIG. 4 conceptually illustrates a semiconductor integrated circuit inaccordance with an embodiment of the present invention.

FIG. 5 is a block diagram of a correction circuit included in a firstsemiconductor chip illustrated in FIG. 4.

FIG. 6 is a timing diagram illustrating a signal transmission method ofthe semiconductor integrated circuit of FIG. 4.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will be described belowin more detail with reference to the accompanying drawings. The presentinvention may, however, be embodied in different forms and should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art. Throughout the disclosure, like referencenumerals refer to like parts throughout the various figures andembodiments of the present invention.

The drawings are not necessarily to scale and in some instances,proportions may have been exaggerated in order to clearly illustratefeatures of the embodiments. When a first layer is referred to as being“on” a second layer or “on” a substrate, it not only refers to a casewhere the first layer is formed directly on the second layer or thesubstrate but also a case where a third layer exists between the firstlayer and the second layer or the substrate.

In the embodiments of the present invention, for example, foursemiconductor chips are stacked. However, the embodiments of the presentinvention are not limited to a semiconductor device that has foursemiconductor chips that are stacked, and more or less semiconductorchips may be stacked.

FIG. 4 conceptually illustrates a semiconductor integrated circuit inaccordance with an embodiment of the present invention.

Referring to FIG. 4, the semiconductor integrated circuit 200 has astructure where a first semiconductor chip 210 has three secondsemiconductor chips 220, 230, and 240 that are sequentially stacked overthe first semiconductor chip 210. The first semiconductor chip 210receives an external signal SIG and is referred to as a master chip. Thethree second semiconductor chips 220, 230, and 240 are controlled by themaster chip and are referred to as slave chips. The master chip and theslave chips may be fabricated through the same process or differentprocesses.

The first semiconductor chip 210 includes a first buffer 211, a clocksignal generator 213, a second buffer 215, and a correction circuit 217.The first buffer 211 is configured to buffer the external input signalSIG and output an internal signal SIG′. The clock signal generator 213is configured to generate an internal clock signal CLK that has adesignated period in response to a test enable signal TMEN. The secondbuffer 215 is configured to buffer the internal clock signal CLK. Thecorrection circuit 217 is configured to reflect a delay time caused bysignal transmission TSVs TSV11, TSV12, and TSV13 corresponding to theposition of the chip in the stack into the internal signal SIG′ and tooutput a first internal input signal SIG1.

The correction circuit 217 uses a first internal clock signal CLK11outputted from the second buffer 215 and a second internal clock signalCLK12 obtained by passing the first internal clock signal CLK11 throughall of the test TSVs TSV21, TSV22, TSV23, TSV33, TSV32, and TSV31provided in the second semiconductor chips 220, 230, and 240. Thecorrection circuit 217 calculates a delay time caused by signaltransmission TSVs TSV11, TSV12, and TSV13 corresponding to the positionof the chip in the stack of the first semiconductor chip 210.

A delay time tDbuf1 caused by the operation of the first buffer 211 maybe equal to a delay time tDbuf2 caused by the operation of the secondbuffer 215. The clock signal generator 213 may generate an internalclock signal CLK having a sufficient period such that the correctioncircuit 217 may calculate a difference in phase caused by the delay timeof the stacked structure.

In addition, the first semiconductor chip 210 further includes a switch219 configured to couple two input terminals of the correction circuit217 in response to a top die signal TOP_DIE. The top die signal TOP_DIEmay be activated, for example, only in the uppermost secondsemiconductor chip 240. The two input terminals of the correctioncircuit 217 receive first and second internal clock signals CLK11 andCLK12.

The three second semiconductor chips 220, 230, and 240 includecorrection circuits 221, 231, and 241, the signal transmission TSVsTSV11, TSV12, and TSV13, first test TSVs TSV21, TSV22, and TSV23, andsecond test TSVs TSV31, TSV32, and TSV33, respectively.

The correction circuits 221, 231, and 241 are configured to reflectdelay times caused by signal transmission TSVs TSV11, TSV12, and TSV13corresponding to the position of each chip in the stack into inputsignals SIG″, SIG′″, and SIG″″ and to output a second to fourth internalinput signals SIG1, SIG2, and SIG3, respectively. The signaltransmission TSVs TSV11, TSV12, and TSV13 are formed vertically throughthe respective second semiconductor chips in a first position andconfigured to transmit the internal input signal SIG′. Because of thedelay on the internal input signal SIG′ caused by the TSVs, the secondconductor chips 220, 230, and 240 receive the input signals SIG″, SIG′″,and SIG″″. The first test TSVs TSV21, TSV22, and TSV23 are formedvertically through the respective second semiconductor chips in a secondposition and configured to transmit the first internal clock signalCLK11 transmitted from the first semiconductor chip 210 to the secondsemiconductor chips 220, 230, and 240. The second test TSVs TSV31,TSV32, and TSV33 are formed vertically through the respective secondsemiconductors at a third position and configured to transmit a secondinternal signal CLK42 back to the first semiconductor chip 210 and thesecond semiconductor chips 220 and 230.

The respective correction circuits 221, 231, and 241 use the firstinternal clock signals CLK21, CLK31, and CLK41 transmitted through thefirst test TSVs TSV21, TSV22, and TSV23 and the second internal clocksignals CLK22, CLK32, and CLK42 transmitted through the second test TSVsTSV31, TSV32, and TSV33, respectively, in order to calculate the delaytimes caused by signal transmission TSVs TSV11, TSV12, and TSV13corresponding to the position of each chip in the stack. Additionally,the three second semiconductor chips 220, 230, and 240 further includeswitches 223, 233, and 243 configured to couple input terminals of therespective correction circuits 221, 231, and 241 in response to the topdie signal TOP_DIE. For example, only the second semiconductor chip 240stacked at the uppermost position may have the switch 243 activated. Theinput terminals receive the first internal clock signals CLK21, CLK31,and CLK41 and the second internal clock signals CLK 22, CLK 32, and CLK42, respectively.

FIG. 5 is a block diagram of the correction circuit 217 included in thefirst semiconductor chip 210 illustrated in FIG. 4.

Although the correction circuit 217 is shown, the correction circuits221, 231, and 241 all have the same configuration as correction circuit217.

Referring to FIG. 5, the correction circuit 217 includes a delay timecalculator 217A and a first variable delayer 217B. The delay timecalculator 217A is configured to calculate a delay time corresponding toa phase difference between the first and second internal clock signalsCLK11 and CLK12. The first variable delayer 217B sets a delay time inresponse to a control signal CTR<0:N> outputted from the delay timecalculator 217A. The first variable delayer 217B is configured to delaythe internal input signal SIG′ by a delay amount that reflects thecalculated delay time that was calculated by the delay time calculator217B.

The delay time calculator 217A includes a second variable delayer 217A_1and a control signal generator 217A_2. The second variable delayer217A_1 has a delay time which is set in response to the control signalCTRL<0:N> and is configured to reflect the calculated delay time intothe first internal clock signal CLK11. The control signal generator217A_2 is configured to generate the control signal CTRL<0:N> inresponse to an output signal of the second variable delayer 217A_1 andthe second internal clock signal CLK12.

Additionally, the control signal generator 217A_2 includes a D flip-flop217A_21, a delayer 217A_23, and a shifter 217A_25. The D flip-flop217A_21 is configured to output the second internal clock signal CLK12in response to the output signal CLK_DELY of the second variable delayer217A_1. The delayer 217A_23 is configured to delay the output signalCLK_DELY of the second variable delayer 217A_1 by a delay time tDdffbased on the operation of the D flip-flop 217A_21. The shifter 217A_25is configured to output the control signal CTRL<0:N> in response to anoutput signal LOCK of the D flip-flop 217A_21 and an output signalCLK_DELY1 of the delayer 217A_23. The D flip-flop 217A_21 and theshifter 217A_25 are reset in response to a reset signal RESET. Forexample, the reset signal RESET may be activated when the semiconductorintegrated circuit 200 is initially driven or when an update operationis performed in a mode that does not transmit the external input signalSIG (for example, standby mode).

The first variable delayer 217B and the second variable delayer 217A_1may include a variable coarse delay line (VCDL). In particular, thedelay time of the first variable delayer 217B may be half of the delaytime of the second variable delayer 217A_1. This process will bedescribed below in detail.

Hereafter, a signal transmission method of the semiconductor integratedcircuit 200 in accordance with the embodiment of the present inventionwill be described.

The signal transmission method of the semiconductor integrated circuit200 in accordance with the embodiment of the present invention may beperformed through two processes. More specifically, the processesinclude a first process of calculating delay times that reflect thedelay times between the respective semiconductor chips 210, 220, 230,and 240 during a test mode, and a second process of reflecting thecalculated delay times into the internal input signals SIG′, SIG″,SIG′″, and SIG′″ transmitted to the respective semiconductor chips 210,220, 230, and 240 during a normal mode.

First, the first process will be described.

When the semiconductor integrated circuit 200 enters the test mode, forexample, only the switch 243 included in the uppermost secondsemiconductor chip 240 is activated in response to the top die signalTOP_DIE. Then, as a test enable signal TMEN is activated, the internalclock signal CLK generated by the clock signal generator 213 is appliedto the second buffer 215.

The first internal clock signal CLK11 buffered through the second buffer215 is applied to the correction circuit 217 and simultaneouslytransmitted to the first test TSV TSV21. Furthermore, the first internalclock signal CLK21 transmitted through the first test TSV TSV21 isapplied to the correction circuit 221 and simultaneously transmitted tothe first test TSV TSV22. Furthermore, the first internal clock signalCLK31 transmitted through the first test TSV TSV22 is applied to thecorrection circuit 231 and simultaneously transmitted to the first testTSV TSV23. Furthermore, the first internal clock signal CLK41transmitted through the first test TSV TSV23 included in the fourthsemiconductor chip 230 is applied to the correction circuit 241. Thesecond internal clock signal CLK42 is obtained by passing the firstinternal clock signal CLK41 through the shorted switch 243. The secondinternal clock signal CLK42 is applied to the correction circuit 241 andsimultaneously transmitted to the third semiconductor chip 230 throughthe second test TSV TSV33. Subsequently, the second internal clocksignal CLK32 transmitted through the second test TSV TSV33 is applied tothe correction circuit 231 and simultaneously transmitted to the secondsemiconductor chip 220 through the second test TSV TSV32. Furthermore,the second internal clock signal CLK22 transmitted through the secondtest TSV TSV32 is applied to the correction circuit 221 andsimultaneously transmitted to the first semiconductor chip 210 throughthe second test TSV TSV31. Furthermore, the second internal clock signalCLK12 transmitted through the second test TSV TSV31 is applied to thecorrection circuit 217.

The phase differences between the first internal clock signals CLK11,CLK21, CLK31, and CLK41 and the second internal clock signals CLK12,CLK22, CLK32, and CLK42 applied to the respective correction circuits217, 221, 231, and 241 will be described. The following descriptions donot include a delay time tDbuf2 by the second buffer 215. First, sincethe first internal clock signal CLK11 applied to the correction circuit217 serves as the reference, the delay time of the first internal clocksignal CLK11 is ‘0*tDtsv’. Since the first internal clock signal CLK21applied to the correction circuit 221 passes through one TSV, TSV21, thedelay time of the first internal clock signal CLK21 is ‘1*tDtsv’. Sincethe first internal clock signal CLK31 applied to the correction circuit231 passes through two TSVs, TSV21 and TSV22, the delay time of thefirst internal clock signal CLK31 is ‘2*tDtsv’. Since the first internalclock signal CLK41 applied to the correction circuit 241 passes throughthree TSVs, TSV21, TSV22, and TSV23, the delay time of the firstinternal clock signal CLK41 is ‘3*tDtsv’. Furthermore, since the secondinternal clock signal CLK42 applied to the correction circuit 241 240has the same delay time as the first internal clock signal CLK41, thedelay time of the second internal clock signal CLK42 is ‘3*tDtsv’. Sincethe second internal clock signal CLK32 applied to the correction circuit231 passes through four TSVs, TSV21, TSV22, TSV23, and TSV33, the delaytime of the second internal clock signal CLK32 is ‘4*tDtsv’. Since thesecond internal clock signal CLK22 applied to the correction circuit 221passes through five TSVs, TSV21, TSV22, TSV23, TSV33, and TSV32, thedelay time of the second internal clock signal CLK22 is ‘5*tDtsv’. Sincethe second internal clock signal CLK12 applied to the correction circuit217 passes through six TSVs, TSV21, TSV22, TSV23, TSV33, TSV32, andTSV31, the delay time of the second internal clock signal CLK12 is‘6*tDtsv’. Accordingly, the phase difference between the first andsecond internal clock signals CLK11 and CLK12 applied to the correctioncircuit is ‘6*tDtsv (6*tDtsv−0*tDtsv)’, the phase difference between thefirst and second internal clock signals CLK21 and CLK22 applied to thecorrection circuit 221 is ‘4*tDtsv (5*tDtsv−1*tDtsv)’, the phasedifference between the first and second internal clock signals CLK31 andCLK32 applied to the correction circuit 231 is ‘2*tDtsv(4*tDtsv−2*tDtsv)’, and the phase difference between the first andsecond internal clock signals CLK41 and CLK42 applied to the correctioncircuit 241 is ‘0*tDtsv (3*tDtsv−3*tDtsv)’.

Therefore, the above-described phase differences are equal to the delaytimes calculated by the respective correction circuits 217, 221, 231,and 241, more specifically, the controlled delay times of the secondvariable delayers 217A_1 included in the respective correction circuits217, 221, 231, and 241. Since the operations of the correction circuits217, 221, 231, and 241 are performed in the same manner, the followingdescriptions will be focused on the correction circuit 217. When thesemiconductor integrated circuit is initially driven, the secondvariable delayer 217A_1 has a delay time of ‘0’ as a default value.Therefore, the second variable delayer 217A_1 outputs the first internalclock signal CLK12 without delay. Then, the D flip-flop 217A_21activates the operation control signal LOCK according to a phasedifference between the delayed first internal clock signal CLK_DELY andthe second internal clock signal CLK12. The shifter 217A_25 generatesthe control signal CTRL<0:N> in response to the operation control signalLOCK of the D flip-flop 217A_21 and the output signal CLK_DELY1 of thedelayer 217A_23. The second variable delayer 217A_1 controls the delaytime in response to the control signal CTRL<0:N>. Accordingly, thesecond variable delayer 217A_1 delays the first internal clock signalCLK11 according to the control signal CTRL<0:N> and repeats theabove-described series of operations. Then, when the phase differencebetween the delayed first internal clock signal CLK_DELY outputted fromthe second variable delayer 217A_1 and the second internal clock signalCLK12 becomes ‘0’, the D flip-flop 217A_21 deactivates the operationcontrol signal LOCK. The shifter 217A_25 locks the control signalCTRL<0:N> according to the deactivated operation control signal LOCK,and the second variable delayer 217A_1 controls the delay time accordingto the locked control signal CTRL<0:N>. After the above describedoperations, the controlled delay time becomes ‘6*tDtsv’, which is equalto the phase difference between the first and second internal clocksignals CLK11 and CLK12.

Next, the second process will be described.

First, the delay time of the second variable delayer 217_A and the firstvariable delayer 217B are controlled by the same control signalCTRL<0:N>. However, the delay time of the first variable delayer 217B iscontrolled by a time corresponding to the half of the delay time of thesecond variable delayer 217A_1. The delay time for the first variabledelayer 217B is half the delay time of the second variable delayer 217_Abecause a delay time is two times larger than a delay time that isactually reflected through the signal transmission TSVs TSV11, TSV12,and TSV13. The delay time is two times larger because the signal used tocalculate the delay time goes through twice as many test TSVs as signaltransmission TSVs. In other words, in the normal mode, since theinternal input signal SIG′ applied to the first semiconductor chip 210serves as the reference, the delay time of the internal input signalSIG′ is ‘0*tDtsv’. Furthermore, since the internal input signal SIG″applied to the second semiconductor chip 220 passes through one signaltransmission TSV TSV11, the delay time of the internal input signal SIG″is ‘1*tDtsv’. Furthermore, since the internal input signal SIG′″ appliedto the third semiconductor chip 230 passes through two signaltransmission TSVs, TSV11 and TSV12, the delay time of the internal inputsignal SIG′″ is ‘2*tDtsv’. Furthermore, since the internal input signalSIG″ applied to the fourth semiconductor chip 240 passes through threesignal transmission TSVs, TSV11, TSV12, and TSV13, the delay time of theinternal input signal SIG″″ is ‘3*tDtsv’. As shown, the delay timethrough the signal transmission TSVs corresponds to the half of thedelay time calculated during the first process.

When the input signal SIG is applied during the normal mode, the inputsignal SIG is buffered into the internal input signal SIG′ through thefirst buffer 211. The buffered internal input signal SIG′ is applied tothe correction circuit 217 and simultaneously transmitted to the signaltransmission TSV TSV11. Then, the correction circuit 217 delays theinternal input signal SIG′ by ‘3*tDtsv’ and outputs the first internalinput signal SIG1. Furthermore, the internal input signal SIG″transmitted through the signal transmission TSV TSV11 is applied to thecorrection circuit 221 and simultaneously transmitted to the signaltransmission TSV TSV12. Then, the correction circuit 221 delays theinternal input signal SIG″ by ‘2*tDtsv’ and outputs the second internalinput signal SIG2. Furthermore, the internal input signal SIG′transmitted through the signal transmission TSV TSV12 is applied to thecorrection circuit 231 and simultaneously transmitted to the signaltransmission TSV TSV13. Then, the correction circuit 231 delays theinternal input signal SIG′″ by ‘1*tDtsv’ and outputs the third internalinput signal SIG3. Furthermore, the internal input signal SIG″″transmitted through the signal transmission TSV TSV13 is applied to thecorrection circuit 241, and the correction circuit 241 delays theinternal input signal SIG″″ by ‘0*tDtsv’ and outputs the fourth internalinput signal SIG4.

Therefore, referring to FIG. 6, it can be seen that skews occurringbetween the respective semiconductor chips 210 to 240 are minimized inthe first to fourth internal input signals SIG1, SIG2, SIG3, and SIG4because of the delays reflected by the correction circuits.

In accordance with the embodiment of the present invention, the internalinput signals SIG1, SIG2, and SIG3 of the semiconductor chips 210, 220,and 230 stacked in the lower portion are delayed by the correspondingdelay times, based on the internal input signal SIG4 of thesemiconductor chip 240 where the delay time is reflected most.Therefore, it is possible to minimize skews occurring between thestacked semiconductor chips. Accordingly, the embodiment of the presentinvention may be applied to a high-speed operation.

In accordance with the embodiments of the present invention, the delaytimes occurring between the stacked semiconductor chips are previouslycalculated and reflected into the signals applied to the semiconductorchips. Therefore, it is possible to minimize skews occurring between thestacked semiconductor chips.

While the present invention has been described with respect to thespecific embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

For example, the control signal generator 217A_2 in accordance with theembodiment of the present invention may include a phase detector and acounter instead of the D flip-flop 217A_21 and the shifter 217A_25. Inaddition, any components may be applied as long as they can calculate aphase difference.

What is claimed is:
 1. A signal transmission method of a semiconductorintegrated circuit which transmits a signal applied from an externalcircuit to the plurality of stacked semiconductor chips, the signaltransmission method comprising: calculating delay times that occurbetween the plurality of stacked semiconductor chips in a test mode; andreflecting the delay times into signals transmitted to the respectivesemiconductor chips and outputting the signals into the respectivesemiconductor chips, in a normal mode, wherein the delay time which isreflected in the normal mode is controlled to be the half of the delaytime which is calculated in of the test mode.
 2. The signal transmissionmethod of claim 1, wherein calculating the delay time in the test modefurther comprises: generating a control signal; sending the controlsignal to a plurality of delayers; delaying a first internal signal;repeating the test mode procedures until the first internal signal and asecond internal signal have a zero phase difference.
 3. The signaltransmission method of claim 1, wherein the calculating delay timesinclude calculating the delay times corresponding to a position of theplurality of semiconductor chips by using an internal signal transmittedthrough the plurality of semiconductor chips.
 4. The signal transmissionmethod of claim 3, wherein the internal signal comprises: a firstinternal signal transmitted in a first direction through the pluralityof semiconductor chips; and a second internal signal obtained byreturning the first internal signal in a second direction through theplurality of semiconductor chips, wherein the second direction is theopposite direction of the first direction.
 5. The signal transmissionmethod of claim 1, wherein the plurality of semiconductor chips comprisea master chip stacked at an uppermost position and at least one slavechip excluding the master chip.
 6. The signal transmission method ofclaim 1, wherein the plurality of semiconductor chips comprise a masterchip stacked at a lowermost position and at least one slave chipexcluding the master chip.